jlc@atux01.UUCP (J. Collymore) (08/23/88)
In article <3510001@hpcvlx.HP.COM>, everett@hpcvlx.HP.COM (Everett Kaser) writes: > (If you haven't seen this IMAX film, only available at the handful of IMAX > theaters around the nation, you MUST see it if you're ever close enough to > an IMAX theater that is showing it!!) Anywayyyyy.... I was AMAZED to > see how much the shuttle swayed over and back between the ignition of the > main engines and the SRBs! I had never seen or noticed this before in the > footage I'd seen on my TV (admittedly, a smaller screen than IMAX). And > the sound system in that theater!!!! Talk about feeling the thunder of the > launch inside your lungs!!! Errrhhhmmm. I ramble. > > Everett Kaser > !hplabs!hp-pcd!everett The reason for the swaying effect that you noticed is launch vehicle gimbaling. This is caused by the force of the Space Shuttle Main Engines (SSMEs) igniting (each engine of the three provides ~255,000 pounds of thrust). This causes the entire launch vehicle to rock/sway/gimbal slightly off full vertical. It takes approximately 6 seconds for the shuttle to return to full vertical. Once it is back in proper position the Solid Rocket Boosters (SRBs) are ignited (providing about 2.9 million pounds of thrust each). This is why you will see the SSMEs ignited at T-minus 6 seconds, and the SRBs ignited at T-minus 0. (I learned all this stuff at U.S. Space Academy in the Adult Level I program.) Also, I saw "The Dream is Alive" this year at the National Air & Space Museum in Washington, D.C. on IMAX. However, it was NOT as good as seeing it in CINEMAX in the SpaceDome theatre (where your screen is basically a planetarium dome which totally surrounds you instead of just being in front of you), at the Space & Rocket Center in Huntsville, Alabama (home of the U.S. Space Camp & Space Academy)! Jim Collymore P.S. Next time you watch the movie, and they give you a "bird's eye view" of the launch, notice the streams of water gushing into a large container beneath the pad. This water acts as a "damper" for the concussion/shock waves created by the SSMEs igniting, and the SRBs. Without this aquatic damper, the shock waves of engine ignition would wreck the launch pad, and the shuttle. (I learned this at Space Academy, also.)